Dental handpiece

ABSTRACT

In a dental handpiece with an elastically arranged reception part ( 8 ) for a tool, compressed air from angled exit nozzles ( 9 ) can be applied to a sleeve ( 7 ) allocated to the reception part ( 8 ) with radial play. The circulating movement of the sleeve ( 7 ) is converted into a vibration of the reception part ( 8 ), the plane of vibration lying essentially perpendicular to the longitudinal axis of the reception part ( 8 ).

DESCRIPTION

[0001] The invention relates to a dental handpiece with a workhead, inwhich a rotation of an element to which compressed air can be applied isconverted into a vibration of an elastically housed reception part for adental tool, the plane of vibration of the reception part lyingessentially perpendicular to the longitudinal axis of the receptionpart.

[0002] Such a handpiece is known from FIG. 6 of AT 404 550 B. Theincoming compressed air acts on an unbalanced turbine rotor which ishoused rotatably on the reception part of the tool so that the rotatingunbalance generates the desired vibrations of the tool (file, brush,polishing tool, etc). The rotary shafts achieve up to 300,000revolutions per minute and very high stresses inevitably occur in theroller bearings.

[0003] The object of the invention is to create a dental handpiece ofthe type mentioned at the outset in which no roller bearings arenecessary.

[0004] This is achieved according to the invention in that thevibration-generating element is formed by a sleeve allocated to thereception part with radial play, towards which angled outlet nozzles forthe compressed air are directed. The compressed air which strikes thewall of the sleeve at an angle effects a circular rolling movement ofthe sleeve and thus generates the rotating unbalance which brings thereception part and the tool clamped into the reception part into naturaloscillations.

[0005] In a first version, the angled outlet nozzles are provided insidethe sleeve in the reception part. The compressed air is supplied to theoutlet nozzles from the axially-distanced inlet chamber via an annularchannel extending axially in the reception part or several axis-parallelchannels.

[0006] In a further version, the angled outlet nozzles are providedoutside the sleeve in an annular element connected to the reception partwhich surrounds the sleeve with radial play. As the annular element isconnected to the reception part, the radial play between the sleeve andthe annular element can be smaller than the radial play between thesleeve and the reception part itself, so that the sleeve circles againstthe internal wall of the annular element and the vibrations aretransferred to the reception part via the annular element. Thecompressed air is supplied in this version via an annular channel whichruns between the annular element and an external sleeve.

[0007] To act on the vibration-generating sleeve from the outside, theoutlet nozzles can also for example be provided at an annular elementarranged in the housing of the workhead.

[0008] For the elastic bearing of the reception part, a first elasticelement in the front area of the reception part and a second elasticelement in the rear area are preferably provided, the second elasticelement preferably sealing off the inlet chamber for the compressed airfrom the exit chamber. The sleeve is preferably arranged behind thesecond elastic element at the end of the reception part.

[0009] The invention is described in more detail in the following bymeans of the figures of the accompanying drawings without being limitedto them.

[0010] There are shown in:

[0011]FIG. 1 a section along line I-I of FIG. 2 through a workhead of ahandpiece,

[0012]FIG. 2 a section along line II-II of FIG. 1

[0013]FIG. 3 a section along line III-III of FIG. 4 through a secondversion, and

[0014]FIG. 4 a section along line IV-IV of FIG. 3.

[0015] A handpiece has a workhead 1, allocated to a grip area not shown,in which a channel 2 for the supply of compressed air and a channel 4for the return air are provided. In the housing 5 of the workhead 1, areception part 8 for a dental tool is provided which contains aconventional clamping jaw which can be activated by a pushbutton 16arranged on the rear side of the housing 5 at the top in the drawing.The reception part 8 is arranged in a front elastic element 10 which isformed by an O-ring and in a disk-shaped rear elastic element 11 in thehousing 5. At the same time, the rear elastic element 11 seals off aninlet chamber 12 for the compressed air entering via channel 2 from anexit chamber 13 which communicates with the channel 4 for the returnair. From the inlet chamber 12, which is provided approximatelycentrally in the housing 5, an annular channel 14 extends rearwards intothe area of a sleeve 7 arranged there which is allocated to thereception part 8 with radial play.

[0016] In the version according to FIG. 1 and 2, the sleeve 7 surroundswith radial play an annular element 15 fixed onto the reception part,which has annuli of angled outlet nozzles 9 in two planes, which leadalmost tangentially from the annular channel 14 ending inside theannular element 15 through the wall of the annular element 15 to theoutside. Emerging compressed air thus strikes at an angle the internalwall of the sleeve 7 which, because of the play, is set in a circulatingmovement about the reception part 8 or the annular element 15. Thecirculating movement generates the rotating unbalance which causes thereception part 8 to vibrate. The sleeve 7 is fixed in axial direction bytwo O-rings 17. The space between the annular element 15 provided withthe nozzles 9 and the sleeve 7 opens into the exit chamber 13surrounding the sleeve 7, so that the air can escape into the return-airchannel 4.

[0017] In the version according to FIGS. 3 and 4, the annular element 15connected to the reception part 8 has an approximately pot-shapedstructure, and a housing chamber open into the exit chamber 13 isprovided between the reception part 8 and the annular element for theloosely inserted sleeve 7. The angled outlet nozzles 9 in the wall ofthe annular element 15 are thus developed outside the sleeve 7, and theexternal and internal diameters are chosen so that the sleeve 7 circlesagainst the inside of the annular element 15, whilst, as can be seenfrom FIGS. 3 and 4, a minimal gap remains relative to the reception part8. To supply the compressed air, the annular channel 14 widens conicallyand ends outside the outlet nozzles 9, the external limit of the annularchannel 14 being formed by an additional external sleeve 18.

1. Dental handpiece with a workhead (1), in which a rotation of anelement to which compressed air can be applied is converted into avibration of an elastically-housed reception part (8) for a dental tool,the plane of vibration of the reception part (8) lying essentiallyperpendicular to the longitudinal axis of the reception part (8),characterized in that the vibration-generating element is formed by asleeve (7) allocated to the reception part (8) with radial play, towardswhich angled outlet nozzles (9) for the compressed air are directed. 2.Handpiece according to claim 1, characterized in that the outlet nozzles(9) are provided inside the sleeve (7) in the reception part (8). 3.Handpiece according to claim 1, characterized in that the outlet nozzles(9) are provided outside the sleeve (7) in an annular element (15)connected to the reception part (8).
 4. Handpiece according to one ofclaims 1 to 3, characterized in that the elastic bearing of thereception part (8) in the housing (5) of the workhead (1) comprises afirst elastic element (10) for the bearing of the front area of thereception part (8) and a second elastic element (11) for the bearing ofthe rear area of the reception part (8), the second elastic element (11)preferably sealing off the inlet chamber (12) for the compressed airfrom the exit chamber (13).
 5. Handpiece according to claim 4,characterized in that the sleeve (7) is arranged behind the secondelastic element (11).